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You are here: Home > Sprinkler School™ > Sprinkler System Basics > Winterizing Your Irrigation System > How To Winterize Sprinkler Components



Valves: Gravity draining of the system will not remove water captured inside the valves. Activating the valves manually or electrically from the timer is not an effective way to drain then. Valves that are not blown out with air must follow this procedure: Any diaphragm style such as the DAS-075, DAS-100, CP-075, CP-100, CPF-075, CPF-100, and EV-100 should be disassembled and drained. Remove the bonnet, solenoid, and diaphragm assembly and drain or sponge any standing water, then reassemble.

Actuator type valves such as the APAS-075, APAS-100, AVG-075, and AVG-100 require removal of the stem and solenoid assembly, check for any standing water in the pipe. Manual valves such as the PAS-075 and PAS-100 may simply be left in the open position for the Winter. Valves that are winterized using the blow out method with compressed air do not require disassembly to remove standing water. Leave the valves in the manual open position to prevent possible repressurization during the Winter. This is accomplished by turning the bleed screw or solenoid counterclockwise, to the open position.

Sprinkler Heads: If your system uses automatic drain valves (Model 16A-FDV) installed properly at the low point of the system, the sprinkler lines will drain automatically each time the system is shut off. This should drain the water from the sprinkler heads also. Some sprinklers have both side and bottom pipe inlets. If you use the side inlet, install a drain valve on the bottom inlet to prevent the case from freezing. Sprinkler heads containing built in check valves to prevent low head drainage require disassembly, or must be blown out with air to achieve proper winterization. These types of heads are usually found only on commercial installations. Sprinklers that have been blown out with air generally do not require and additional treatment.

Timers: Several methods for winterizing timers are available. Some may be more appropriate for your particular application, depending on the model you own, systems utilizing water pumps require special attention here. Read the entire section before deciding which method is correct for you.

  1. If your sprinkler system does not have a water pump and your timer has a programming dial or a mechanical on/off switch: Turn the timer to the "OFF" position. Leave the timer plugged in. The program you set will remain intact. You may leave the back up battery plugged in on electronic models. Leaving the timer plugged in keeps some heat inside the unit, warding off condensation which may be harmful to the circuit board. Timers such as the ISA-304, ISA-406, ISA-408, PC-506, ESP-12LXi, ESP-16LXi, or any mechanical timer like the RC-7C series (the type that has pins and dials), may simply be turned to OFF, RAIN, or RAIN/OFF to achieve proper winterization.

  2. If your sprinkler system does not have a water pump and your digital electronic timer has a "keypad" only: Press the "SYSTEM/OFF" or "AUTO/OFF" key. This will turn the system off, leaving the program in the memory. A single digit flashing in the display indicates the system is interrupted, giving visual confirmation. Caution! A power surge or prolonged power failure could cause the timer to default back to the automatic mode, sending a signal to the irrigation control valves or pump to come on. This will not hurt the valves, but could do serious damage to a "dry" running pump. Examples of this type of timer are the PC-104, PC-106, PC-204, PC-206, TSC-7, EZ-1, and the CRC-4/6/8.

  3. If your sprinkler system has a water pump and your timer is in an indoor digi-tal electronic or mechanical model: Unplug the timer. Turning the timer off from the keypad does not guarantee complete security from the timer coming on again in case of a power surge or power failure. Mechanical models turned off from the switch can just as easily be reactivated. Indoor models have a power cord attached to a transformer style plug. Simply unplug the transformer from the power source. The transformer is a small black box that is usually warm or hot to the touch. Warning! Grabbing a hot transformer could cause burns. Use gloves to protect your hands. Next, remove the backup battery (digital models) to prevent it from discharging over the Winter. Be advised that this method causes the program to disappear on digital models. You will have to reprogram the timer next spring. Examples of this type of timer are the PC-104-P/S, PC-106-P/S, PC-204-P/S, PC-206-PS, TSC-7, EZ-1, and RC-7Bi (or any Rain Bird RC-Bi or RC-I series).

  4. If your sprinkler system has a water pump and your timer is an outdoor digital electronic or mechanical model, follow these steps carefully: Turning the timer off from the keypad does not guarantee complete security from the timer coming on again in case of a power surge or power failure. Mechanical models turned off from the switch can just as easily be reactivated. To correctly winterize these types of timers, the common wire(s) running to the pump start relay and the valves must be disconnected from the timer. Turn the power source to the timer off at the main circuit breaker panel for your home or garage first. These timers are "hard wired" directly into the high voltage circuit of your electrical system. The power wires run directly through conduit pipe to the timer. Warning! Touching high voltage wires can cause electrical shock and burns. Do not attempt to disconnect these wires to de-power the timer. The power may only be turned off at the main circuit breaker panel. Verify that the power is completely off by removing the backup battery. Wait for 2 minutes. If the digital display on the timer has not gone blank, please call Rain Bird, or an irrigation contractor to assist you. If you have verified that the power is off to the timer, proceed to disconnect the wire or wires marked "Common", "Com", or "C", on the timer terminal strip. This is the location in the timer where the valve wires connect. Usually there is a row of screws that are labeled and numbered. Locate the terminal designated as COMMON, COM, or C. In some cases there may be 2 terminals marked for the common wire. Disconnect all of the wires from the common terminal. Twist a wire nut or place a piece of electrical tape over any loose wire ends to prevent the wire(s) from touching and causing a short circuit. Reconnect the backup battery on digital models.

    Mechanical models:
    Many Rain Bird mechanical timers have a valve wiring harness that may simply be unplugged to disconnect the common and station wires altogether. This is usually a white multi-pin "snap" connector (Molex type) located behind the face panel, inside the cabinet. Close the timer access panel. Turn the power source back on to the timer. Be sure to go ahead and program the timer to the "OFF" setting on the keypad or switch. Set the station timing to zero minutes for all of the stations to prevent any operation. In the Spring, reconnect the common wires and reprogram the timer.

Backflow Preventer:
Please check with the manufacturer for specific winterization techniques. Leave the shutoff valves open after draining the unit. "Ball" type shutoff valves should be left at a 45 degree angle to prevent water from entering the seal. Under extreme conditions, insulate the device or use "heat tape" to prevent damage.

Pump: Please check the pump manufacturer’s instructions for winterization. See timer section regarding pumps.

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